Tue May 17, 2022 9:59 pm
The issue you described is a timing issue - where all the pixel data is correct on the connection, but the sender and receiver disagree on the timing of what means what. Different recieving devices will have different tolerances on the range of signals they accept, so if you've got a borderline acceptably timed signal, different devices will react differently.
How to fix? First try another resolution - it may be that you can find a resolution that the atem is quite happy with that meets your requirements. If that doesn't work, see if there are driver options for refresh rate and/or timing. Intel in particular allow a lot of control over their timing information for motherboards (I know not relevant in this case), but if you change them sufficiently you can make any monitor give up - if you've got access to the settings, try changing them and see if the atem behaves. If you still have no luck, try looking for devices that will reclock/retime the signal, such as a decimator.
Unfortunately this is one of those "it's simple, just plug it in and it works" issues where there's actually a load of complicated stuff going on behind the scenes that means it's actually far from simple, and you've found a combination that doesn't work.